Automatic return device for control members



Aug. 23, 1938.

F. FREITAG AUTOMATIC RETURN DEVICE FOR CONTROL MEMBERS Filed Feb. 3, 1938 Patented Aug. 23, 1938 2,127,909

UNITED STATES PATENT OFFICE AUTOMATIC RETURN DEVICE FOR CON- TROL MlElVIBERS Friedrich Freitag, Wallstadt, Germany, assignor to Zellstofifabrik Waldhof, Mannheim-Waldhof, Germany, a joint-stock company of Germany Application February 3, 1938, Serial No. 188,591 In Germany March 28, 1936 1 Claim. (Cl. 74-501) This application corresponds to the application A construction of the invention is shown by of Zellstofifabrik Waldhof, Serial No. Z.23108, way of example in the accompanying figure. which was filed in Germany on 28th March, 1936. At A is shown the starting pulley of an electric For allowing starters or control switches for motor. By exerting a pull on one of the cables 5 electric motors and the like devices (for example, or chains B1 and B2, the pulley can be rotated to valves in gas and liquid conveying conduits and the left or to the right out of the zero position, a the like) which are adapted to be moved in either motor being thereby switched for lifting or lowerdirection out of a zero position by means of two ing. For example, if the chain B1 is pulled, the oppositely acting pull members to return autochain B2 passing through the bore G2 is raised matically into the zero position again on releasand its lifter C2 carries the weight D2 with it, the 10 ing the pull members, spiral leaf springs have latter being guided in a tube E2. Instead of exgenerally been employed. In this case two ternal guide tubes E2, guide rails or internal guide springs are necessary, namely a spring for the tubes may be used. Upon releasing B1, the return of the starter from each direction, the weight B2 by bearing on the lifter C2 presses the tension produced in said spring by the pulling chain B2 downwardly until it has returned into 15 being liberated on release and the apparatus beits inoperative position F2. The starting pulley ing automatically returned into its centre posi- A is thereby turned back and the starter returns tion. to its zero position. Further running down of Automatic return by means of spiral springs the chain 132 is prevented by abutment of the has, however, considerable disadvantages. The lifter C1 of the chain B1 against the weight D1 20 springs which are encased in a housing are not which has remained in the inoperative position easily accessible, are troublesome to clean, foul F1.

and stick easily and require frequent repairs, Upon pulling the chain B2, the same cycle while fracture of the springs is comparatively occurs in respect of the weight D1 moving in frequent, the entire apparatus being thereby put the guide E1 and provided with a bore G1. 25

out of operation. I claim:

According to the invention, these disadvantages In mechanism for effecting return to a neutral are obviated and a satisfactory return of the position of a control device displaceable in either device into the central position and hence a redirection from such position, the combination liable and undisturbed operation of the appawith a pulley operatively connected to the con- 30 ratuses may be ensured by arranging on each trol device, a flexible member passing over said pull member a weight which is raised upon a pulley and having generally vertical runs, an pull being exerted on the opposite member, and abutment connected to each of said runs, a upon release returns into the stationary inoperweight supported for engagement by each of said ative position. abutments, each of said weights being positioned 35 If the apparatus is in its central position, the for engagement by the associated abutment on two weights also occupy their inoperative posiinitiation of movement of the flexible member tions by resting for example on a stationary supin a direction toraise such abutment and the port or being suspended from a stationary device. weight engaged thereby, whereby on release of 10 In order that the weights will be able to .move the flexible member, the weight thus raised will 10 up and down within certain limits defined by return the flexible member and the pulley to the lifters or the like'mounted on the pull members, initial position thereof, and stationary means each of said weights is provided with a preferably cooperating with each of said weights to guide central bore, through which the pull member the latter in the direction of the associated runs passes. In order to ensure satisfactory sliding of said flexible member.

of the weights, it is expedient to allow them to run in guides, for example on vertical rails or FRIEDRICH FREITAG.

in tubes. 

